Protein-protein interaction (PPI) network
To illustrate the interactions among the DEPs proteins, we carried out a
PPI network analysis with all the DEPs at different Ca levels. A total
of 28 proteins were matched to the PPI network (Figure 5, Supplementary
Table S1). Node degree is a critical index to evaluate the importance
and correlation of proteins in the PPI network. As shown in Figure 5 and
Table S2, ten proteins with a degree over 6 were observed. The top 5
proteins according to their degrees were ranked as heat shock protein 70
(HSP70), enolase (LOS2), cytosolic ascorbate peroxidase (APX1), 2-Cys
peroxiredoxin BAS1 (AT3G11630) and ATP synthase subunit beta (PB),
suggesting their central roles in the interaction network. Multiple
biological processes may be influenced by these central nodes.
A total of 4 highly enriched interaction function modules including
photosynthesis, carbohydrate metabolism, oxidation stress response and
chaperones were observed in the PPI network, suggesting exogenous Ca
possibly mediated these physiological and metabolic processes in growingP. massoniana seedlings. The links among proteins belonging to
different biological processes and pathways indicate there are potential
crosslinks among Ca influenced diverse biological processes and
metabolism pathways in P. massoniana seedlings.